<!DOCTYPE html>
<style>
body,
iframe {
    aspect-ratio: 1;
}

body {
    display: -webkit-box;
    -webkit-box-orient: block-axis;
}

iframe {
    display: block;
    -webkit-box-flex: 1;
    max-inline-size: min-content;
}
</style>
<script>
if (window.testRunner)
    testRunner.dumpAsText();

onload = () => {
    let iframe0 = document.createElement('iframe');
    document.body.append(iframe0);
    document.body.getBoundingClientRect();
    iframe0.style.position = 'fixed';
    document.body.getBoundingClientRect();
    document.body.innerHTML = "This test PASS if it doesn't CRASH.";
};
</script>
</html>